From: Andrew Morton <akpm@linux-foundation.org>
To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: len.brown@intel.com, wency@cn.fujitsu.com,
linux-acpi@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
paulus@samba.org, minchan.kim@gmail.com,
kosaki.motohiro@jp.fujitsu.com, rientjes@google.com,
cl@linux.com, linuxppc-dev@lists.ozlabs.org, liuj97@gmail.com
Subject: Re: memory-hotplug : suppres "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" warning
Date: Fri, 5 Oct 2012 14:09:38 -0700 [thread overview]
Message-ID: <20121005140938.e3e1e196.akpm@linux-foundation.org> (raw)
In-Reply-To: <506D1F1D.9000301@jp.fujitsu.com>
On Thu, 4 Oct 2012 14:31:09 +0900
Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> wrote:
> When our x86 box calls __remove_pages(), release_mem_region() shows
> many warnings. And x86 box cannot unregister iomem_resource.
>
> "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>"
>
> release_mem_region() has been changed as called in each PAGES_PER_SECTION
> chunk since applying a patch(de7f0cba96786c). Because powerpc registers
> iomem_resource in each PAGES_PER_SECTION chunk. But when I hot add memory
> on x86 box, iomem_resource is register in each _CRS not PAGES_PER_SECTION
> chunk. So x86 box unregisters iomem_resource.
>
> The patch fixes the problem.
>
> --- linux-3.6.orig/arch/powerpc/platforms/pseries/hotplug-memory.c 2012-10-04 14:22:59.833520792 +0900
> +++ linux-3.6/arch/powerpc/platforms/pseries/hotplug-memory.c 2012-10-04 14:23:05.150521411 +0900
> @@ -77,7 +77,8 @@ static int pseries_remove_memblock(unsig
> {
> unsigned long start, start_pfn;
> struct zone *zone;
> - int ret;
> + int i, ret;
> + int sections_to_remove;
>
> start_pfn = base >> PAGE_SHIFT;
>
> @@ -97,9 +98,13 @@ static int pseries_remove_memblock(unsig
> * to sysfs "state" file and we can't remove sysfs entries
> * while writing to it. So we have to defer it to here.
> */
> - ret = __remove_pages(zone, start_pfn, memblock_size >> PAGE_SHIFT);
> - if (ret)
> - return ret;
> + sections_to_remove = (memblock_size >> PAGE_SHIFT) / PAGES_PER_SECTION;
> + for (i = 0; i < sections_to_remove; i++) {
> + unsigned long pfn = start_pfn + i * PAGES_PER_SECTION;
> + ret = __remove_pages(zone, start_pfn, PAGES_PER_SECTION);
> + if (ret)
> + return ret;
> + }
It is inappropriate that `i' have a signed 32-bit type. I doubt if
there's any possibility of an overflow bug here, but using a consistent
and well-chosen type would eliminate all doubt.
Note that __remove_pages() does use an unsigned long for this, although
it stupidly calls that variable "i", despite the C programmers'
expectation that a variable called "i" has type "int".
The same applies to `sections_to_remove', but __remove_pages() went and
decided to use an `int' for that variable. Sigh.
Anyway, please have a think, and see if we can come up with the best
and most accurate choice of types and identifiers in this code.
next prev parent reply other threads:[~2012-10-05 21:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-04 5:31 memory-hotplug : suppres "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" warning Yasuaki Ishimatsu
2012-10-05 19:01 ` KOSAKI Motohiro
2012-10-05 21:09 ` Andrew Morton [this message]
2012-10-09 2:51 ` Yasuaki Ishimatsu
2012-10-09 21:39 ` Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121005140938.e3e1e196.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=isimatu.yasuaki@jp.fujitsu.com \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=len.brown@intel.com \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=liuj97@gmail.com \
--cc=minchan.kim@gmail.com \
--cc=paulus@samba.org \
--cc=rientjes@google.com \
--cc=wency@cn.fujitsu.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).